It seems like most of you are on the metric basndwaogn. So much is this going to cost? I hadn't read anyone mention it costs money to convert to metric. maybe I missed it. The highway system alone should cost millions. Every mile marker and tenth mile marker would need to be replaced and repositioned. And every exit would have to be renumbered. We've spent years changing sequencial exit numbers to match mile markers. And how about speed limit signs. There are no dual posted speed where I live. And replacing all the maps.

Look in 37 years I would think that every thing that needed to convert to metric has and evrything that didn't, hasn't. So what's the benefit in converting what's not metric to metric and is it worth the cost? We seem to be getting along just fine with a mixed system.

I totally agree that it is time to go metric. I work at a European company that is 100% metric. We do not carry spares of Standard bolts because all equipment (even equipment built in the US) is 100% metric. It was easier to adjust to the metric constraints than I thought it would be.

Seem like I remember the US trying to convert to the metric system when I was a child back in 19??. This was many many years after 1920 lol. I wasn't a driver but think I saw speed limit signs with both number systems displayed.

The remark about inflating tires makes the point, but not the way it is intended. The basic unit, the pascal, is a very small, mostly useless unit. So metric-descriptions for hydraulic pressure seem to use other units. Likewise, measurements of length is most often in cm or mm, because the basic unit, the meter, is a bit bigger than our yard. The yard approximates to a running step, making it good for football announcers. For all of my design work over the years I have used inches, and decimal fractions thereof. Then there is no confusion for the folks using the drawings.

For hydraulics, pressures in PSI multiplied by cylinder diameter give forces in pounds, with no conversions to other units needed. Consider: 250kPa x 100cm2=?

Now for bolt sizes the strength ratio between inch-sized bolts is far more useful than it is for metric bolt sizes. That is because many design engineers select bolts based on the load that they need to carry. While the metric math is simpler, the sizes are not as intuitive.

Really, all that we would have needed to do was to get rid of the standard fractional system of measurement and moved on to decimal fractions, and our system woulde have been so very much simpler.

I lived in the USA for over 20 years and I have just returned to Australia which had a successful conversion to SI/metric in the early seventies.

There was a government mandate with a carefully considered plan and time limit. (The conversion was actually completed well before the time limit.)

There was no transition period where dual measurements were used. People just stopped using the ancient measurements. Road signs were converted in a single day. We bought our tomatoes in kg rather than lb, we drove at speed limits in km/h and that was it. Note that we never used hectograms like the Canadians. That is just weird. All food prices are per kg, not per 100g.

This is not to say that phrases like "six feet under" and "a mile a minute" suddenly disappeared from the culture to be replaced by silly metric equivalents. Even today people still talk occasionally in feet and acres.

It may be a bit surprising but the people who adopted the metric system quickest and loved it the most were construction workers. Their lives suddenly became much easier. No longer were dimensions on plans given as things like 13 ft 9 7/8 in. Instead that dimension would appear as 4207. Note the absence of units. It is always mm. Simple.

A corollary to that is avoid the use of cm in most cases. 4207 is better than 420.7 cm.

For those who love the old units, remember this. The US was one of the first countries in the world to use a decimal coinage, abandoning the British system of 4 farthings to the penny, 12 pence to the shilling and 20 shillings to the pound. Consider how much easier it is to add $4.70 and $2.85 than to add £2/14/3½ and £1/10/11¾. Would anyone even contemplate going back to that sort of system? Yet the US retained the 18th Century British measurements which are equally complex.

I have heard people say that the old British measurements are somehow more "natural" than metric ones. Really? How is the length of three barley grains laid end to end relate to everyday life? Yet that is what an inch supposedly represented. (Now it is defined as 25.4 mm exactly). Is a foot really the size of someone's foot? Certainly not mine, or my wife's or my grandson's. A meter, by contrast, is pretty close to the median height of the population (including all ages) and is arguably more natural than the foot. 100 mm is about the width of my hand (including the thumb) and a liter is the volume occupied by a box one hand width on each edge and whien filled with water weighs 1 kg. What, by contrast is a gallon? In the US it is 231 cubic inches and corresponds to the Queen Anne wine gallon. How natural is that? What is a pound? The weight of what? What is the relationship between a fluid ounce and an ounce weight? What is the difference between a dry quart and a liquid quart?

We all know from school days how far 100 m is. It is the distance between the start and finish line of a common and fairly short foot race. Make a square with that distance on each side and you have a hectare, the common land measurement. It is easy to visualise. Now picture an acre. What exactly does that look like? It was supposed to represent the amount of land a horse could plough in a day. Do you have a horse and one of those single-furrow ploughs?

Yes there are costs associated with conversion. However for the most part they are one-off costs but failing to convert incurs recurrent costs in terms of dual tooling, difficulty in penetrating world markets and unnecessary complexity in education, construction and everyday life. Furthermore as others have pointed out, the failure to effect a speedy conversion actually increases the costs because materials in metric sizes are in short supply and hence more expensive.

Australia did it. New Zealand did it. South Africa did it. We now reap the benefits. It is about time that the USA did it too.

This whole discussion is completely pointless, folks. There is absolutly no need to "adopt" the Systeme International (don't count on anyone but Americans' knowing what you mean by the "metric system") because back about 1860, believe it to not, the US Congress passed a law saying Americans could use the SI if they wanted to. The SI has been a ratified American standard for some time now and is covered (with a few mistakes) in ANSI SI 6 [? I might have the number wrong]. The kind of people who can benefit from the SI, can easily use it in their products...or not (excpet for getting that pesky lower-case, Greek mu to appear correctly in all media). There is no need to cram SI units down the throats of ordinary Americans. I too have no use for how many km it is from Harrisbug to Philly and I certainly have no need to know how many cm it is! There are a few things that Americans could learn about the SI. Firstly, it is an international standard so pronounciations are standardized too. Just like Carl Sagan used to inton, its "kilo-meter/metre" not "kuh-lom'-eter." And no, captial-K is not the multipoier for 1000; lower-case "k" is (captial "K" is the abbreviation for kelvin - which never takes a degree sign but celcius does). And there is no micorn; it's now micrometer (pronounced "micro-meter/metre" and not "my-crom'-eter"). The rules for pluralization vary from language to language, and some languages do not make this rahter pointless distinction at all. So SI 6 is in error when it specifies English pluralization conventions. The plural of "henry" is NOT "henries"l SI units are simply never pluralized (RPMs for that matter too). As for abbreviations, you have at least three choices for the abbreviation of liter/liter (both spellings are standard). The abbreviations for minutes and seconds are "m" and "sm" not "min" and "sec," sorry. While the micron is no more, if you are a phycist, your beloved angstrom is safe. And if you are an commercial airline pilot you are required to measure distance in nautical miles and altitude in feet (just thought that the metrication fanatics reading this would like to know that when they are a passanger on any country's airline, the pilots are usint Imperial units. YIKES!)

The US nearly converted to the metric system around 1920. Many technical publications from around that time were in the metric system. Now no. 100 years on the religious and political structure of the US will not allow such a change.

Under he first Jerry Brown term as governor of California he has the state go metric. We bought liters of gas and drove kilometers instead of miles. The next governor was George Deukmejian who reversed it back.

I agree that we should go metric but there are many idiots in this country that think this is a subversive foreign French plot for World government under the World Bank or who knows, maybe the Yale Yacht Club.

It's long overdue and will probably have to be introduced by the Republican Party in order not to be considered subversive (like the Nixon trip to China).

It's the political fringe that makes the most noise and now with the Internet the fringe is in high gear and amplified beyond belief.

There have been several high profile aerospace mistakes made by using two systems and getting confused. Several have involved rocket launches and even a Mars probe that didn't make it. There are probably thousands of such mistakes that are costly in terms of money and perhaps even lives that aren't reported in the press.

Jon, I retired from GE in 2005 and at that time we did just as you have suggested; i.e. use English and Metric dimensions. The metric dimensions were enclosed in brackets, [ ]. All of the CAD work accomplished for GE Appliances is done in India by a company called Satyam. One of the major reasons drawings and literature are in both systems is the need for a "global" presence. Even in the appliance business, GE has markets in the USA, Latin America, Asian and Western Europe. I still have problems going back and forth but as I read drawings in using both I have adapted somewhat to the "other" system. Like Ann, I have two sets of tools in my work room; one for the Kirby vacuum and one for my Toyota truck.

A few weeks ago, Ford Motor Co. quietly announced that it was rolling out a new wrinkle to the powerful safety feature called stability control, adding even more lifesaving potential to a technology that has already been very successful.

It won't be too much longer and hardware design, as we used to know it, will be remembered alongside the slide rule and the Karnaugh map. You will need to move beyond those familiar bits and bytes into the new world of software centric design.

People who want to take advantage of solar energy in their homes no longer need to install a bolt-on solar-panel system atop their houses -- they can integrate solar-energy-harvesting shingles directing into an existing or new roof instead.

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